2.) IDENTIFY ANY SIGNIFICANT FINDINGS AND RESULTS OF THE PROJECT TO DATE.

Transcription

1 PROGRESS REPORT PROJECT TITLE: Enhancement of Survey Efforts for Corn Pests in Minnesota PROJECT NUMBER: SP REPORTING PERIOD: 2nd quarter (July1- September 30, 2018) PRINCIPAL INVESTIGATOR: Bruce Potter ORGANIZATION: University of Minnesota PHONE NUMBER: (507) ) PROJECT ACTIVITIES COMPLETED DURING THE REPORTING PERIOD. (Describe project progress specific to goals, objectives, and deliverables identified in the project workplan. Objective I. Improve and expand the current trapping networks for corn insect pests a) Black light trap network operating (Hutchison) Trap operation for 2018 concluded in mid-september. Data for European corn borer (ECB), western bean cutworm (WBC) and true armyworm (TAW) are available at the UMN VegEdge website ( moth data) during the growing season. Light trap captures of true armyworm helped predict and reinforce reports of infestations in corn and small grains. b) Pheromone trap network (Hutchison/Potter) Black cutworm No activity this quarter For 2018, the corn earworm trapping at multiple locations also concluded in mid- September (corn earworm pheromone trap captures). These trap captures helped provide early warning for managing this pest in sweet corn production as well as a useful predictor for damage to field corn (due to late planting), particularly non-bt. c) Corn rootworm sticky trap (Ostlie) Sticky trap data from the summer of 2018 are being collected from industry collaborators and the observations collated by the Ostlie lab. These data will become increasingly important as Bt resistance and on-farm economics change the selection pressure on rootworm populations. Objective II: Develop a network of sentinel and on-farm survey plots for corn insect pests and corn diseases a) Corn disease monitoring at U of M ROCs (Malvick/Potter) i. Develop and use sentinel plots for determination of the annual prevalence of key corn pathogens and insects.

2 Sentinel plots were planted adjacent to foliar fungicide study at Waseca, Rosemount, Lamberton, Morris and Crookston locations. Mid and late-season disease ratings have been made but analyses are not yet complete. The incidence of northern corn leaf blight was related hybrid with lesions much more common on susceptible indicators. Physoderma symptoms were observed in susceptible indicator plots at the Lamberton and Waseca locations but at very low incidence. ii. Evaluate yield loss corn foliar fungal pathogen losses by comparing fungicide applications with untreated controls at multiple locations. Fungicide studies were planted at the Waseca, Rosemount, Lamberton, Morris and Crookston and fungicide treatments applied at all locations. Yield data will be analyzed during November and December of 2018 (3 rd quarter). b) On-farm corn insect and pathogen monitoring (Fall survey for European corn borer and corn pathogens) i. Conduct a statewide fall survey for overwintering larval corn borer populations to estimate on annual geographic populations and project following year's risk The 2018 survey began in September 2018 and completed October 2018 (3 rd quarter). A total of 207 commercial fields were sampled, and thanks to grower and crop consultant cooperators, this included a total of 70 known non-bt fields. No significant change in the 2018 ECB infestation levels were observed compared to For the non-bt fields, we found an average of 0.039/plant (27 larvae total), whereas the randomly sampled fields (137) averaged only 0.008/plant (11 larvae total). Briefly, the overall population estimate for all commercial fields combined was 0.018/plant in 2018, reflecting historically low levels. ii. iii. Use larvae collected during the statewide fall survey to determine geographic differences in corn borer voltinism biotypes. Due to low infestation levels of ECB, larvae were collected but from fewer fields than in The larvae are now in diapause in the Hutchison lab. Conduct a statewide survey for corn foliar diseases to determine annual prevalence of key species. We recorded the incidence of stalk rots during the fall corn borer survey. In SW and portions of SC and WC Minnesota, we recorded data on several additional corn diseases. 2.) IDENTIFY ANY SIGNIFICANT FINDINGS AND RESULTS OF THE PROJECT TO DATE. I a) Light trap captures predicted low European corn borer populations overall (Fig 1). Fall survey data also indicated this to be true. UMN Extension received reports of economic infestations

3 from parts of WC MN but these appear to have been isolated. The positive observations of larval infestation in SW MN are related to longer-term Bt use. When combined with the temperaturedependent development maps developed by the Hutchison lab (Fig 2), corn growers and their advisors now have additional tools to refine scouting efforts for fields planted to conventional hybrids or those without an above-ground Bt trait. Unlike several other Midwestern states, 2018 western bean cutworm captures in MN were very low. However, unlike previous years, several black light traps did capture moths during 2018 (Fig. 3). Because of documented resistance to Bt traits, this insect needs to remain on the watch list of MN corn insect pests. The light trap network did capture several flights of true armyworm (Fig. 4). This correlated with damage to corn (primarily conventional) associated with a winter rye cover crop or grassy weeds and to small grains. If the use of cover crops increases, true armyworm could become a more consistent pest of corn. I b) Flights of corn earworm were captured in multiple pheromone trap locations. Numbers were high enough in several locations to trigger an alert for corn earworm in sweet corn. Because many fields of dent corn in southern MN Minnesota were planted late, fields planted to a hybrid without an above ground Bt trait had unusually heavy infestations of corn earworm in ear tips. In addition to reports from ag professionals, fall corn borer surveys in the SW part of the state found earworm damage in ear tips of non-traited corn. I c) In process II a) i. In process ii. In process II b) i. Fall surveys for damage caused by European corn borer (Fig 6) and population density of overwintering larvae (Fig 7) were completed by early 3 rd quarter. Two hundred seven (207) fields were surveyed; 70 of these were non-bt fields whose locations were provided by farmer cooperators (Fig 8). Preliminarily, overall populations are low and similar to As expected, known non-bt fields provided a higher probability of finding corn borer infestations than fields selected at random (Fig. 8, 9). As in previous years, the probability of finding corn borer in randomly selected fields is greatest in EC, C and NW Minnesota areas that presumably have a greater prevalence of non-bt corn. However, we suggest that the sampling of insect pests in non-bt fields is important in areas with a higher adoption of Bt in order to understand risks and population changes in corn borer and other insect pests across MN. ii. In process

4 iii. Disease data collected during corn borer survey are currently being analyzed. Stalk rot observations, based on push tests, were recorded for most of the fields surveyed (Fig 10). Due, in part to high winds, stalk lodging was severe in many MN fields. There is likely a bias in stalk rot data based on maturity stage of the crop when sampled. For example, parts of SW and SC MN were sampled earlier than other areas and ratings would likely be higher if observations had been taken later. 3.) CHALLENGES ENCOUNTERED. (Describe any challenges that you encountered related to project progress specific to goals, objectives, and deliverables identified in the project workplan.) I a) It is unfortunate that the performance of pheromone traps for European corn borer is sporadic. Obtaining additional light traps and operators has been more difficult than anticipated. II b) i. To this point, it has not been possible to obtain the percentages of non-bt planted at a finer resolution than state level. Regional hybrid trait data resides with seed companies and remains proprietary. County and field level data resides with growers. Knowing where higher densities of Bt are planted would greatly improve our ability to design and interpret corn insect data. To obtain this type of data, a simple survey to be distributed during winter educational meetings, and perhaps through MN Corn, is planned. II b) iii. As mentioned previously, disease symptoms are dependent on corn growth stage. This complicates obtaining accurate information when a fall corn borer survey is scheduled. Too early and stalk rots and ear molds are underestimated. Too late and foliar disease symptoms are no longer visible. For 2019, a standardized system to solicit disease incidence from ag professionals will be explored. 4.) FINANCIAL INFORMATION (Describe any budget challenges and provide specific reasons for deviations from the projected project spending.) A change in salary class and travel for the Hutchison lab requested and approved in September (Appendix A). 5.) EDUCATION AND OUTREACH ACTIVITES. (Describe any conferences, workshops, field days, etc attended, number of contacts at each event, and/or publications developed to disseminate project results.) Black light trap data for Lepidopteran pests and corn earworm have been posted since June 1 at: Maps of temperature dependent degree-day models for predicting European corn borer development and scouting and treatment windows are being posted at

5 Alerts for true armyworm. Corn earworm, and other corn pests were distributed through the SW MN IPM stuff newsletter, MN Crop News blog, and ag news print and radio media outlets. Fig European corn borer black light captures

6 Fig 2. End of season example of degree-day prediction for development of the multi-voltine and uni-voltine strains of ECB. Source:

7 Fig western bean cutworm black light captures Fig true armyworm black light trap captures. Flights before July pose the greatest risk to corn.

8 Fig 5. Counties with economic infestations of true armyworm. Infestations in corn, small grain, and pasture/hay crops reported to UMN Extension during 2018.

9 Fig 6. Fig 7.

10 Legend: White (no corn borer found), yellow tunnels but no larvae, red tunnels and larvae found. Fig. 8. Fields surveyed for European corn borer populations during 2018 (left) cooperator fields planted to non-bt hybrids (right). Fig. 9. A comparison of overwintering corn borer populations based on fields chosen at random (left) and based on known non-bt fields provided by cooperators (right).

11 Fig Stalk rot incidence. Percent of stalks affected below ear.

12 Appendix A Request for Revised budget of MN Corn Growers grant (Year 1), to Hutchison, Dept. of Entomology, *Project # , "Enhancement of Survey Efforts" *Correct Acct# now included, to reflect the Year 1 award (now: 3/31/17 to 4/1/19) To: MN Corn Growers, Paul Meints (PMeints@mncorn.org) Fr: Bill Hutchison, Entomology Regarding the current budget for Year 1 funds, that were extended to support Year 2 work as well, I am requesting two changes, as a better use of the remaining funds: a) change the employee salary/fringe line, from: Undergraduate student, to: standard Civil Service category The UG salary line has $3,499 remaining, not yet spent due to UG student needs on other projects, and the work for the Fall Survey, Data entry, requires additional supervision, etc. A better fit for these funds will be to apply these to my existing parttime staff, Suzanne Wold-Burkness (Civil Service), who is the key person summarizing weekly ECB and CEW moth flight data, and posting the data (graphs) weekly on the VegEdge web site; and this is part of our work for the grant. She also posts the Annual Fall Survey Maps for ECB on various web sites; and maintains these with historical maps, and for various newsletter articles, etc. To also keep the budget on track, toward the current end date of 4/1/2019, I request approval to add Suzanne, at a part-time rate (Civil Service category, and fringe rate approx. 27.5%) on this project such that these funds will be spent in a timely manner. b) change from travel funds, to also support salary/fringe for Burkness: Of the current balance for travel support ($1,230), I request that $1,000 be transferred from travel, to the Burkness sal. line, to further support this effort. Additional travel $ provided in Year 2 of grant (separate acct #) will be sufficient to cover our travel for the Fall ECB Survey in Reply by: Fax ( ) or to: hutch002@umn.edu Let me know of any questions. Thanks again for your support of this project. Bill Hutchison cc Bruce Potter